Stackable tube assembly



FIG. 1 is a front perspective view of the stackable tube assembly;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a back side view thereof;

FIG. 5 is a front view thereof;

FIG. 6 is a left side view thereof; and,

FIG. 7 is a right side view thereof. 

The ornamental design of a stackable tube assembly, as shown. 